In recent years, a display apparatus called “Dual View Display” is known for use in a vehicle. The Dual View type display apparatus displays two different images on one screen to be viewed simultaneously from two different viewing directions.
When the Dual View type display apparatus is used in a navigation apparatus, it is convenient for the occupants in both of the driver's seat and the passenger's seat because respective occupants see a different image that serves their respective purposes appropriately. However, when the occupants in the driver's seat and in the passenger's seat are viewing respectively different images, whether an operation instruction is inputted in association with the content of the image by the driver or by the passenger has to be distinguished by the navigation apparatus. In this case, if two operation unit are separately disposed for the driver's seat and for the passenger's seat, the origin of the operation instruction can be easily distinguished. That is, the operation instruction inputted from the operation unit on the driver's seat side is determined as the instruction from the driver, and the operation instruction inputted from the operation unit on the passenger's seat side is determined as the instruction from the passenger. However, the restriction on the space or position for installing the operation unit in the vehicle makes it difficult to have separate operation units for both of the driver's seat and the passenger's seat.
Therefore, an idea of single operation unit that can be used by both of the driver and the passenger is in consideration. In that case, an instruction inputted from the single operation unit has to be attributed to one of the two operators, that is, to the driver or to the passenger by some means.
For example, a technique disclosed in Japanese patent document JP-A-2005-284592 uses two operation icons respectively for a viewer A and for a viewer B in a dual view display apparatus having a touch panel. The two operation icons are displayed in a non-superposing manner with each other for distinguishing an operation on the touch panel either by the driver or the passenger.
However, the technique described above has a restriction on the number of the operation icons on the screen as well as a restriction on an arrangement of the operation icons on the screen. Therefore, the usability of the display apparatus using the above technique is deteriorated in comparison to the normal display apparatus having only one image on the screen.